31
INSTALLATION
excel HE -
Installation and Servicing
41 GENERAL CHECKS
Make the following checks for correct operation:
1.
Hot water
a.
Fully open all DHW taps in turn and ensure that water
flows freely from them.
b.
Close all taps except the furthest one from the boiler
and check that the boiler is firing at maximum rate.
c.
Ensure that DHW temperature rise of approximately
40
o
C is obtained at the tap. This corresponds to a
flow rate of approximately:
8.4 (1.8) l/min (gpm)
excel HE C24
10 (2.2) l/min (gpm)
excel HE C28
11.5 (2.6) l/min (gpm)
excel HE C32
Note.
Quoted flow rates and temperature rises are
those theoretically achievable. Flow rates measured
during commissioning may differ (due, for example, to
resistance of domestic hot water pipe lengths and
fittings or available dynamic gas pressures).
If necessary reduce the flow rate using isolation valve
'S'. Refer to Frame 39.
d.
Turn off the DHW tap.
2.
Central heating
Operate each control separately and check that the main
burner or circulating pump, as the case may be, responds.
3.
Gas rate
Check the boiler gas rate when the boiler is at full output.
The gas rate will normally be
45.8 (1.62) litres/min (ft
3
/min) for the model
excel HE C24
53.5 (1.89) litres/min (ft
3
/min) for the model
excel HE C28
62.1 (2.19) litres/min (ft
3
/min) for the model
excel HE C32
checked at the gas meter, with no other appliance in use.
If this check is not possible, ensure that the burner pressure
is:
13.4 (5.3) mbar (in. w.g.) for the model
excel HE C24
10.5 (4.2) mbar (in. w.g.) for the model
excel HE C28
12.9 (5.2) mbar (in. w.g.) for the model
excel HE C32
In addition ensure the dynamic inlet pressure is 20mb.
4.
Water circulation system. Refer to frame 6.
Note.
A suitable flushing solution should be used during
the flushing procedure.
a.
With the system HOT examine all water connections
for soundness.
b.
With the system still HOT, turn off the gas, water and
electricity supplies to the boiler and drain down, to
complete the flushing process.
c.
Refill the system, adding inhibitor (see 'Water
Treatment'), if required. Refer to Frame 10
d.
Balance the system. It is suggested that, initially, all
radiator handwheel valves (or TRVs if fitted) be set
fully open, that all lockshield valves be set a half-turn
open.
Make minor adjustments to each radiator to achieve the
same differential on all.
Finally, set the system controls to the users requirements.
If an optional programmer kit is fitted refer to the
instructions supplied.
40 INITIAL LIGHTING . . . . . CONTINUED
13. DOMESTIC HOT WATER
With the boiler firing, set the DHW thermostat knob (C) to
maximum and fully open a DHW tap. The boiler should
continue to run and provide hot water at the open tap.
Green operational lights 1 and 3 (E) will be illuminated
when burner is lit.
14.
Turn off the tap.
15.
Test for gas soundness around ALL boiler gas
components using leak detection fluid.
16.
Operate for 10 minutes to stabilise the burner temperature.
17.
The boiler is preset at the factory to its maximum output.
Check the burner pressures against the values quoted in
Table 2 (page 4) by using the following procedure.
i.
Remove plastic protective cap from the mechanical
pressure adjustment components (L&K).
ii.
Start the boiler at its maximum power. Operate the
boiler in DHW mode or ensure that the boiler is not
range rated if the test is carried out in CH mode.
Maximum valve setting - CH & DHW
Note.
The minimum CH pressure is automatically set
electronically.
iii.
If necessary, rotate the
maximum
gas pressure
brass hexagon nut adjustment (K) using a spanner
until you obtain the required pressure as indicated on
Table 2 (page 4) (burner pressure). By rotating
clockwise the pressure increases.
Minimum valve setting - DHW Only
iv.
Disconnect one of the two connectors (U).
v.
If necessary, rotate the
minimum
gas pressure
adjustment (red cross point screw) (L) until you
obtain the required pressure as indicated on Table 3
(page 4) (burner pressure). By rotating clockwise the
pressure increases.
vi.
Turn the boiler off and re-connect the wire to the
modulating operator (U).
vii.
Start the boiler and check again the maximum gas
pressure setting.
viii.
Turn the boiler off and disconnect the inlet and burner
pressure gauges and close the gas valve inlet and
outlet pressure test points (J & M).
IMPORTANT.
After the gas pressure checks and any adjustment
operations, all of the test points must be sealed and leak
tested.
18.
Refit the front panel and bottom panel.
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